Emerging viruses in marine mammals.

Abstract

Emerging infectious disease has become a serious concern that has consequences for human, animal and environmental health on a global scale. During the past two decades, it has become clear that viruses are emerging in terrestrial environments from the human-animal interface at an unprecedented rate. Thus, the understanding of complex diseases associated with emerging zoonotic pathogens and the creation and execution of strategies to deal with this issue has assumed new public health importance, requiring a One Health approach involving multiple health disciplines. Similar infectious disease trends involving emerging viruses are now being documented in aquatic ecosystems and are impacting marine mammals. As in terrestrial species, emerging viruses in marine mammals may be associated with neoplasia, epizootics and zoonotic disease and involve a complex pathogenesis involving noninfectious cofactors such as anthropogenic toxins, biotoxins, immunologic suppression and other environmental stressors. Among the viruses recently isolated from marine mammals are influenza viruses, morbilliviruses, papillomaviruses, herpesviruses, arboviruses, caliciviruses and others. Many of these emerging marine mammal viruses are associated with disease and specific pathologic findings. In other cases, the disease significance of these novel viruses is unknown and requires further research. In this report, we briefly review emerging viruses that have disease significance for marine mammals and/or public health. Novel concurrent clinicopathologic data will be presented when available broadening the understanding of disease pathogenesis. References will help provide more in-depth information. Additionally, this review has demonstrated that marine mammals may be important sentinel animals that indicate environmental health concerns and parallel emerging public health issues.

Diseases and parasites

“…Although titers indicate prior exposure and/or infection, no disease was recognized in these bowhead whales. Type-specific antibodies to various caliciviruses have been detected in other baleen whales from the North Pacific ( Bossart and Duignan, 2018 ). In a recent retrospective study where select tissues (liver, kidney, spleen, and lung) from bowhead whales ( n = 59; 2011–15) were tested by polymerase chain reaction (PCR) for a suite of viral pathogens (morbillivirus, adenovirus, paramyxovirus, influenza A virus, Pan-corona virus; herpes virus); adenovirus (10%; 6/59) was the only viral agent detected.…”

“…Recent serological and gross pathological evidence indicates active Brucella infections (granulomatous testis) in several baleen whales (common minke whale, Bryde’s whale, and sei whale) in the western North Pacific ( Ohishi et al, 2016 ). As the Arctic ecosystem continues to undergo a system-wide transformation, regularly updated surveys of bowhead whales on the prevalence of microbial agents known to globally impact cetaceans ( Bossart and Duignan, 2018 ) are crucial to provide current baseline health data.…”

Coronaviruses in the Sea

“…To date there have been no Betacoronaviruses recovered from any marine animal. However, Alphacoronaviruses and Gammacoronaviruses are described in marine mammals (reviewed in Schütze, 2016;Bossart and Duignan, 2018). These include the Harbor Seal Alphacoronavirus (Bossart and Schwartz, 1990), Pacific Harbor Seal Gammacoronavirus (Nollens et al, 2010), Beluga Whale Gammacoronavirus (Mihindukulasuriya et al, 2008) and the Bottlenose Dolphin Gammacoronavirus (Woo et al, 2014).…”

Gray Whale (Eschrichtius robustus) Health and Disease: Review and Future Directions

“…Calicivirus antibodies (San Miguel Sea Lion Virus; SMSVTypes 1, 2, and 3) were detected in five out of 16 (31%) California gray whales processed during 1968-1970 at the San Francisco whaling station (Akers et al, 1974). Vesivirus serotypes have been detected in other baleen whales including fin (Balaenoptera physalus), sei (Balaenoptera borealis), and bowhead whales (Balaena mysticetus) (for review, see Bossart and Duignan, 2018) typically associated with blistering skin disease, with variable lesion size (1-3 cm).…”

“…Surprisingly, there are only scant data, mostly single case reports, on lesions, diseases, marine biotoxins, and infectious diseases of gray whales, although the helminth fauna have long been described (Rice and Wolman, 1971;Dailey and Brownell, 1972). The detection and characterization of infectious agents, especially viruses, in marine mammals have increased considerably; however, establishment of a causal association between pathogens and clinical presentation or pathology for many agents has been difficult "due to inconsistencies in marine mammal morbidity/mortality investigative effort and the logistical and economic limitations for adequate pathologic investigations" (Bossart and Duignan, 2018). This is particularly true for gray whales, with limited studies available.…”